What is behind the recent spike in drug seizures?

What is behind the recent spike in drug seizures?
Nine of those states, as well as Washington, D.C., have legalized recreational possession and use of marijuana. And it isn’t just the state patrol. In Mankato, authorities say they’re seeing more marijuana. The Minnesota River Valley Drug Task Force has seized twice as much marijuana concentrates last …
Source: washington DC marijuana
What is behind the recent spike in drug seizures?